Rock drill bit



March 28, 1950 J c, -n5 2,502,128

ROCK DRILL BIT Filed April 50, 1948 Patented Mar. 28, 1950 ROCK DRILL BIT John 0. Curtis, Claremont, N. H., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application April 30, 1948, Serial No. 24,162

14 Claims.

This invention relates to rock drill bits and more particularly to rock drill bits of the impact type having hard metal inserts set in the cutting face of the bit to provide wear resisting cutting edges.

In rock drill bits of the impact type, in order to reduce rapid wear of the bit, hard metal inserts, usually of tungsten carbide, are, in known instances, secured in slots cut in the bit face to provide wear resisting cutting edges. In the manufacture of such drill bits, considerable difficulty has been encountered in the securing of the hard metal inserts in place in the slots on the bit face to prevent loosening of the inserts in the slots and endwise displacement of the inserts in the slots toward the center of the bit, under the terrific impact action encountered during use of the bit in drilling rock, resulting in direct contact of the inserts and rapid breakage and release thereof. The present invention contemplates improvements over rock drill bits of known types in that the hard metal inserts are firmly held in place in the slots so that loosening and release of the inserts and endwise displacement of the inserts in the slots toward the bit center are substantially avoided.

An object of the present invention is to provide an improved rock drill bit. Another object is to provide an improved rock drill bit having hard metal inserts set in the cutting face to provide wear resisting cutting edges. Another object is to provide an improved rock drill bit wherein the hard metal inserts are secured in position on the bit face in an improved manner. A further object is to provide an improved rock drill bit of the impact type having hard metal inserts secured in slots cut in the front face of the bit body and improved means for preventing loosening and endwise displacement of the inserts in the slots toward the bit center, thereby reducing the possibility of direct contact of the inserts and resultant breakage and release. Yet another object is to provide an improved means for securing the hard metal inserts in the slots on the front face of the bit body wherein means is provided for preventing endwise displacement of the inserts in the slots toward the bit center and having portions overlying projections on the inserts for preventing outward release of the inserts from the slots. object is to provide an improved securing member secured to the bit body and having transverse surfaces lying in planes perpendicular to the bit axis and engaging complemental surfaces on the inserts. A still further object is to pro- Another vide improved abutment means arranged centrally of the bit for preventing inward displacement of the hard metal inserts in the slots and having a transverse surface to which transverse surfaces on the inserts are secured. Another object is to provide an improved securing means for the hard metal inserts for locking the inserts against forward release from the slots on the bit face. Yet another object is to provide an improved central abutment means which is interlocked, in a novel manner, with the hard metal inserts. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompanying drawing there are shown for purposes of illustration several forms which the invention may assume in practice.

In this drawing:

Fig. 1 is a view in central longitudinal section taken through a rock drill bit constructed in accordance with a preferred illustrative embodiment of the invention.

Fig. 2 is a cross-sectional view taken on line 22 of Fig. 1.

Fig. 3 is a front end view of the drill bit shown in Fig. 1.

Fig. 4 is a detail sectional view taken on line d t of Fig. 1.

Fig. 5 is an enlarged perspective view of one of the hard metal inserts of the bit shown in Figs. 1 to 4 inclusive.

Fig. 6 is a view in central longitudinal section illustrating a rock drill bit of modified construction.

Fig. '7 is a cross-sectional view taken on line 'l-'! of Fig. 6.

Fig. 8 is a front end view of the drill bit shown in Fig. 6.

Fig. 9 is a. fragmentary central longitudinal sectional View illustrating another modified construction.

Fig. 19 is a cross-sectional Iii-40 of Fig. 9.

Fig. 11 is a front end view of the drill bit shown in Fig. 9.

Fig. 12 is a fragmentary central longitudinal sectional view illustratin still another modified construction.

Fig. 13 is a cross-sectional view taken on line 3-H of Fig. 12.

Fig. 14 i a front end view of the drill bit shown in Fi 12.

In the several illustrative embodiments of the invention, the rock drill bit generally comprises a body I suitably shaped, as by forging, and

view taken on line having an enlarged forward portion 2 of generally cruciform shape providing cross wings 3. The body is slightly rearwardly tapered and has an integral rearward threaded stud 4 adapted for connection to a usual socketed drill rod. Formed axially in the bit body and stud is a cleansing fluid passage 5. Cut in the front face of the bit body centrally of the cross wings 3 are diametric slots 6 arranged in substantially right angular relation and extending completely across the bit. Extending rearwardly of the drill bit on the exterior of the bit body between the wings are longitudinal recesses or grooves l. Evidently, the invention may be embodied in drill bits of various other shapes.

Now referring to the preferred illustrative embodiment shown in Figs. 1 to 5 inclusive, it will be noted that hard metal inserts 9, preferably of tungsten carbide, are secured as by brazing in the slots E at the opposite sides of the center of the bit. with the inner ends of the inserts spaced. from the bit center. Arranged centrally of the bit is a flanged annulus or abutment ring it cured, as by brazing, to the front face of the bit body at the bottoms of the slots, and this rin has a central opening i l with which the cleansing fluid passage 5 communicates. The inserts, at their inner portions near their inner ends, have inward projections or tongues 42 which underlie the flange l3 of the annulus it. The enacting, transverse, overlapping surfaces of the annulusflange and the insert-tongues are disposed in planes perpendicular to the bit axis. The insertton' ues l2 are preferably secured, as by brazing, to the annulus Hi, and the inner ends of the inserts abut the annulus. Endwise displacement of the inserts 9 in the slots 6 toward the center of the bit is prevented by the annulus iii, and the flange IS on the annulus overlying the tongues 12 on the inserts reduces the possibility of forward release of the inserts from the slots. The inserts are provided with cutting portions projecting forwardly from the slots, and these cutting portions have relatively inclined faces id converging forwardly and meeting along straight cutting edges [5. The inner end faces of the inserts are concaved or arcuately formed at it to fit against the outer peripheral surface of the annulus-flan e l3, as shown in Figs. 2 and 3. The front face of the bit body has a central circular recess l! in which the annulus or ring is fitted, and the ring is secured to the side walls of the rece s. as by brazing, at I 8. The curved inper end faces l6 of the inserts lie substantially flu h with the walls of the central recess H. The cutting portions of the inserts are so formed as to provide radially extending spaces 19 between the inner adjacent ends of the inserts to permit free flow of clean ing fluid from the central circular recess I! transversely of the front face of the bit body to the longitudinal passages or recesses l. Thus cleansing fluid may flow freely through the central pas age 5 and central opening l of the annulus to the central recess ll and then transversely across the cutting face of the bit through the spaces 19 and rearwardly of the bit through the peripheral recesses or grooves l, in a manner conventional in drill bits of the type disclosed.

In the modified construction shown in Figs. 6 to 8 inclusive, hard metal inserts 2U, likewise preferably of tungsten carbide, are secured as by brazing in the slots 6 in the front face of the bit body, and these inserts are formed with cutting portions projecting forwardly from the slots and having relatively inclined faces 2! converging forwardly and meeting along straight cutting edges 22. Formed in the front face of the bit body below the bottoms of the slots 6 in coaxial relation with and surrounding the cleansing fluid passage 5 is an annular groove 23, and an abutment ring 24 has its inner portion secured as by brazing in this groove. The inserts, at their inner surfaces near their inner ends, are re cessed at 25, and the inner curved surfaces 2:3 along the longitudinal outer walls of these re cesses engage the circular exterior surface of the abutment ring 24. The outer surfaces 21 of these insert recesses lie in a plane perpendicular to the bit axis and overlap and engage the plane outer surface of the ring. The wall surfaces of the recesses 26 are preferably secured as by brazing to the ring. The bit body has a central circular recess 28 within which the inner ends of the inserts project, and the cleansing fluid passage 5 communicates with this recess through the open center 29 of the ring. The ring is fitted in the recess 28 and is secured, a by brazing, to the recess walls. Thus a circular central recess is provided which terminates at its bottom in the groove 23, with the inner ends of the inserts, in this instance, extending inwardly into the recess to the walls of the ring opening 253. Cleansing fluid may flow from the recess 28 transversely of the bit face through radial grooves or recesses 36 intermediate the inserts to the longitudinal grooves or recesses l on the bit periphery.

In the modified embodiment shown in Figs. 9, 10 and 11, hard metal inserts 3i, also preferably of tungsten carbide, are secured as by brazing in the slots 6, and these inserts provide wear resisting cutting edges 32. The inner edges of the inserts are recessed or notched at 33 between their ends, and secured, as by brazing, in the insert recesses 33 is a split abutment ring comprising semi-circular parts 35 secured together, as by brazing, at 3E. The inserts have inner projections or tongues 31, at their inner ends, underlying the split ring and upper projections or tongues 38 overlying the split ring, with the engaging surfaces of the insert and ring in planes perpendicular to the bit axis. The split ring is preferably secured, as by brazing at 39, to the side walls of a central circular recess 58 in the front face of the bit body and in which the ring is fitted. The abutment ring prevents enclwise displacement of the inserts toward the bit center and locks the inserts against forward release from the slots. Under certain circumstances, a solid annulus or ring may be substituted for the split ring, and when a solid ring is employed, the inserts and ring must .be brought in assembled relation prior to brazing in the slots in the bit body. In both instances, the ring Would be firmly interlocked with the inserts when the parts are in assembled relation.

In the modified construction shown in Figs. 12, 13 and 14, hard metal inserts 12, preferably of tungsten carbide, providing straight cutting edges 33, are secured as by brazing in the slots 5 in the front face of the bit body, with the inner ends of the inserts spaced from the center of the bit. Coaxial with the cleansing fluid passage 5 and surrounding the latter is a relatively deep annular groove a l having a curved inner wall. An abutment ring 45, having a curved inner edge, is secured as by brazing in the groove and the inserts, at their inner surfaces near their inner ends, are recessed at 46 to receive the outer portion of the ring. The inserts are secured, as

by brazing at 41, to the outer periphery of the abutment ring and are secured at 48, likewise as by brazing, to the plane outer surface of the abutment ring. The front face of the bit body is circularly recessed at 49 to receive the abutment ring 45, and the ring is secured, as by brazing at 50, to the recess walls. Thus the circular recess 49 terminates at its bottom in the annular groove 44. In this instance, the inserts project inwardly from the slots 6 into the central recess 49, as shown. The cleansing fluid passage 5 opens into the open center 5! of the abutment ring and communicates with the central bit recess 43. The bit body has a circular portion 52 surrounding the passage 5 and fitting, as shown in Fig. 12, within the open center 5! of the ring 45. The upper recess surfaces on the inserts and the plane outer surface of the abutment ring lie in a plane perpendicular to the bit axis. The inserts, at their inner ends, abut the abutment ring, and the latter serves to prevent endwise displacement of the inserts toward the bit center.

In the several embodiments above described, the complemental transverse abutting surfaces on the inserts and abutment ring, which are described above as lying in a plane perpendicular to the bit axis, may be said to lie in a surface of revolution of which the generatrix is at an angle to the bit axis; and while shown lying in a plane, perpendicular to the bit axis, they, evidently, may lie in a surface of a cone the elements of which lie at a slight angle to a plane perpendicular to the bit axis. Thus such complemental surfaces may be disposed slightly out of a plane perpendicular to the bit axis, and it is not desired to limit the disposition of these surfaces to a single plane.

As a result of this invention, an improved rock drill bit is provided having hard metal inserts secured, in a novel manner, in slots cut in the front face of the bit body to provide wear resisting cutting edges. By the provision of the central abutment ring secured to the bit body and with which the inner ends of the inserts engage, endwise displacement of the inserts in the slots toward the bit center is prevented. By the provision of transverse surfaces on the inserts overlapping and secured to a complemental transverse surface or surfaces on the abutment ring, the inserts are firmly secured against forward release from the slots. Not only are the inserts firmly secured in position, but also the structure is relatively simple and rugged in design. Other advantages of the invention will be clearly apparent to those skilled in the art.

While there are in this application specifically described several forms which the invention may assume in practice, it will be understood that these forms of the same are shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

l. A rock drill bit of the impact type comprising a body having a diametric slot out completely across its front face, hard metal inserts providing wear resisting cutting edges secured by brazing in said slot at the opposite sides of the bit center and with the inner ends of said inserts spaced from the bit center, and an abutment ring secured by brazing to said bit body centrally of the'bit and with which the inner ends "of said inserts abut for preventing endwise displacement of said inserts toward the bit center, the inner ends of said inserts being recessed to receive said ring, said recesses providing transverse surfaces lying in a plane perpendicular to the bit axis and overlapping and engaging a complemental transverse surface of said ring, and said surfaces of said inserts being secured by brazing to said transverse ring surface.

2. A rock drill bit of the impact type comprising a body having a diametric slot out completely across its front face, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slot at opposite sides of the center of the bit with the inner ends of said inserts spaced from the bit center, and a flanged abutment ring secured by brazing to the front face of said body centrally of the bit, said inserts having tongues underlying the flange of said ring, the inner ends of said inserts abutting the external surface of said ring for preventing endwise displacement of said inserts in said slot toward the bit center, and said insert tongues coacting with said ring flange beneath the latter to prevent forward release of said inserts from said slot.

3. A rock drill bit of the impact type comprising a body having diametric slots cut in right angular relation in the front face of said body completely across the bit, said bit body having a central recess into which said slots enter, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slots with their inner ends spaced from the center of the bit, and a central abutment ring secured by brazing in said central recess and with which the inner ends of said inserts abut for preventing endwise displacement of said inserts in said slots toward the center of the bit, said inserts at their inner ends being arcuately recessed to receive said ring and said insert recesses providing transverse surfaces lying in a plane perpendicular to the bit axis and overlapping and secured by brazing to a transverse surface of said abutment ring.

4. A rock drill bit of the impact type comprising a body having diametrlc slots cut in substantially right angular relation in its front face completely across the bit and a central cleansing fluid passage, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slots with their inner ends spaced from the center of the bit, and an abutment ring secured by brazing to said body centrally of the bit and with which the inner ends of said inserts abut, said inserts being arcuately recessed at their inner edges to receive said ring and providing transverse surfaces lying in a plane perpendicular to the bit axis and overlapping and secured by brazing to a complemental transverse surface of said ring, and said ring having an open center with which said cleansing fluid passage communicates and through which fluid flows to the cutting face of the bit.

5. A rock drill bit of the impact type comprising a body having diametric slots cut in substantially right angular relation in its front face completely across the bit, said body having a central recess in its front face and a central cleansing fluid passage, hard metal inserts providing wear resisting cutting edges and secur d by brazing in said slots with their inner ends spaced from the center of the bit, and an abutment ring arranged in said central recess and secured by brazing to said bit body, said inserts at their inner ends abutting said ring and being arcuately recessed at their inner edges to receivesaid ring, said inserts having projections overlying the outer surface of said ring and secured by brazing to said outer ring surface, and said ring having an open center through which cleansing fluid flows from said central passage to said central recess.

6. A rock drill bit of the impact type comprising a body having a diametric slot cut in its front face completely across the bit, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slot at opposite sides of the center of the bit with the inner ends of said inserts spaced from the bit center, and a split abutment ring arranged centrally of the bit and secured by brazing to said bit body, said ring comprising semi-circular parts brazed together when assembled and secured in position on the bit body, said inserts at their inner edges being arcuately notched to receive said ring and providing inner and outer transverse surfaces lying in spaced parallel planes perpendicular t the bit axis and overlapping and engaging the inner and outer transverse surfaces of said ring whereby said ring and said inserts are rigidly interlocked together.

7. A rock drill bit of the impact type comprising a body having a diametric slot cut in its front face completely across the bit, said body having a central circular recess in its front face, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slot at opposite sides of the center of the bit with the inner ends of said inserts spaced from the bit center, and a split abutment ring fitted in said central recess and secured by brazing to the recess walls, said ring comprising semi-circular parts brazed together when assembled and brazed in position in said recess, said inserts at their inner edges being arcuately notched to receive said ring and providing inner and outer transverse surfaces lying in spaced parallel planes perpendicular to the bit axis and overlapping and engaging the inner and outer transverse plane surfaces of said ring whereby said ring and said inserts are rigidly interlocked together.

8. A rock drill bit of the impact type comprising a bod having a diametric slot cut in its front face completely across the bit, said body having an annular groove formed therein at the bottom of said slot in coaxial relation with the bit, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slot at the opposite sides of the center of the bit, and an abutment ring having its inner portion received in said annular groove, said inserts bein arcuately recessed at their inner ends to receive said ring and said insert recesses providing transverse surfaces lying in a plane perpendicular to the bit,

inserts providing wear resisting cutting edges and secured by brazing in said slot at opposite sides of the center of the bit, and an abutment member arranged centrally of the bit and secured to said bit body, said abutment member having lateral portions, the inner ends of said inserts abutting said abutment member and said inserts having tongues underlying said lateral portions of said abutment member and said tongues having surfaces lying in a plane perpendicular to the bit axis and overlapping and engaging complemental surfaces on the bottoms of said lateral portions of said abutment member.

10. A rock drill bit of the impact type com- '8 prising a body having a diametric slot cut in its front face completely across the bit, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slot at opposite sides of the center of the bit, and an abutment member arranged centrally of the bit and secured to the bit body and with which the inner ends of said inserts externally abut, said inserts being recessed at their inner ends to receive portions of said abutment member, and said recesses providing parallel spaced apart transverse surfaces each lying in a plane perpendicular to the bit axis and overlapping and engaging a complemental transverse surface on said abutment member.

ll. A rock drill bit of the impact type comprising a body having a diametric slot cut completely across its front face, hard metal inserts providing wear resisting cutting edges secured by brazing in said slot at the opposite sides of the bit center and with the inner ends of said inserts spaced from the bit center, and an abutment ring secured by brazing to said bit body centrally of the bit and with which the inner ends of said inserts externally abut for preventing endwise displacement of said inserts toward bit center, the inner ends of said inserts being arcuateiy recessed to receive said ring, said recesses providing transverse surfaces lying in a surface of revolution of which the generatrix is at an angle to the bit axis and overlapping and engaging a complemental transverse surface of said ring, and said surfaces of said inserts being secured by brazing to said transverse ring surface.

12. A rock drill bit of the impact type comprising a body having diametric slots cut in right angular relation in the front face of said body completely across the bit, said bit body having a central recess into which said slots enter, hard metal inserts providing wear resisting cutting edges and secured by brazing in said slots with their inner ends spaced from the center of the bit, and a central abutment ring secured by brazing in said central recess and with which the inner ends of said inserts externally abut for preventing endwise displace ment of said inserts in said slots toward the center of the bit, said inserts at their inner ends being arcuately recessed to receive said ring and said insert recesses providing transverse surfaces lying in a surface of revolution of which the generatrix is at an angle to the 'bit axis and overlapping and secured by brazing to a transverse surface of said abutment ring.

13. A rock drill bit of the impact type comprising a body having a diametric slot cut in its front face completely across the bit, said body having an annular groove formed therein at the bottom of said slot in coaxial relation with the bit, hard metal inserts providing Wear resisting cutting edges and secured by brazing in said slot at the opposite sides of the center of the bit, and an abutment ring having its inner portion received in said annular groove, said inserts being arcuately recessed at their inner ends to receive said ring and said insert recesses providing transverse surfaces lying in a surface of revolution of which the generatrix is at an angle to the bit axis and engaging and ecured by brazing to a transverse surface of said ring,

i l. A rock drill bit of the impact type comprising a body having a diametric slot cut in its front face completely across the bit, hard faces each lying in xnetal inserts providifig wear resisting cutting edges and secured byvgbrazing in said slot at opriosite sides of the "benter of the bit, and5an "abutment member arranged centrally of the bit and secured to the bit; body and with which lthe fiinner ends of said inserts externally abut, said inserts being arcuateiy recessed at their inner ends to receive portions of said abutment member, and said recess providing transverse {sursurface of revolution of [which the generatr" is at an angle to the bit axis and overlapping and engaging a complemental transverse surface on said abutment member.

JOHN C. CURTIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

